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The Amateur Seismology Package
User's Manual
Rev 1.2.0 (September 25, 1991)
Copyright (c) 1991 Robert K. Samuelson. All rights reserved.
Dept. 256
4215 Winnetka Ave. N.
New Hope, MN 55428 USA
The Amateur Seismology Package User's Manual 1
Table of Contents
1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Copyright Notices . . . . . . . . . . . . . . . . . 3
1.2 Disclaimer . . . . . . . . . . . . . . . . . . . . 4
1.3 Distribution . . . . . . . . . . . . . . . . . . . 4
2.0 User Support . . . . . . . . . . . . . . . . . . . . . . 4
3.0 Data File Distribution . . . . . . . . . . . . . . . . . 5
4.0 Bibliography . . . . . . . . . . . . . . . . . . . . . . 6
5.0 SEISGRAPH . . . . . . . . . . . . . . . . . . . . . . . 9
5.1 Overview . . . . . . . . . . . . . . . . . . . . . 9
5.2 Installation . . . . . . . . . . . . . . . . . . . 9
5.3 Guided Tour . . . . . . . . . . . . . . . . . . . . 10
5.4 Features . . . . . . . . . . . . . . . . . . . . . 13
5.4.1 Invoking SEISGRAPH . . . . . . . . . . . 13
5.4.2 Reading Data Files . . . . . . . . . . . 13
5.4.3 Adjusting X Limits . . . . . . . . . . . 13
5.4.4 Adjusting Y Limits . . . . . . . . . . . 14
5.4.5 Autorange . . . . . . . . . . . . . . . . 14
5.4.6 Guide Window . . . . . . . . . . . . . . 15
5.4.7 Data Window . . . . . . . . . . . . . . . 15
5.4.8 Printing . . . . . . . . . . . . . . . . 15
5.4.9 Setup String . . . . . . . . . . . . . . 16
5.4.9.1 b (Binary File) . . . . . . . . . . 16
5.4.9.2 e (Eight Bit File) . . . . . . . . . 17
5.4.9.3 x (Skip Bytes) . . . . . . . . . . . 17
5.4.9.4 c (Color) . . . . . . . . . . . . . 17
5.4.9.5 a (Autorange) . . . . . . . . . . . 18
5.4.9.6 s (Samples Per Second) . . . . . . . 18
5.4.9.7 b (Bin Size) . . . . . . . . . . . . 18
5.4.9.8 p (Printer Port) . . . . . . . . . . 18
5.4.9.9 d (Printer Driver) and r
(Resolution) . . . . . . . . . . . . . . 19
5.5 Data File Format . . . . . . . . . . . . . . . . . 20
5.6 Problems and Solutions . . . . . . . . . . . . . . 20
6.0 How Data Files Are Created . . . . . . . . . . . . . . . 22
7.0 The Future . . . . . . . . . . . . . . . . . . . . . . . 23
1.0 Introduction
The Amateur Seismology Package is a collection of programs, data
files, and documentation which allows users of IBM (*1)
compatible personal computers to load seismic data files and
print seismograms.
Seismograms are graphs of the motion of the Earth's surface at a
given location due to the passing waves caused by a distant
earthquakes and can be used to determine, among other things, the
distance between the earthquake and the recording station's
location.
The Amateur Seismology Package is intended for use by 'amateur
scientists' and students who are interested in the Earth sciences
in general and seismology in particular. The package will allow
users to study seismograms of recent earthquakes using data files
distributed by the author. The data files are produced by the
author's seismometer and recording system.
Data files for notable events will be distributed as quickly as
practical. Data files which are contaminated with noise or
contain little of interest will probably not be distributed
unless requested by a user who has also recorded the event.
ALL DATES AND TIMES ASSOCIATED WITH SEISMIC DATA WILL BE IN
COORDINATED UNIVERSAL TIME (UTC), ALSO KNOWN AS GREENWICH MEAN
TIME (GMT) OR 'ZULU' (Z).
Rather than explain the science of seismology and the practices
of seismometry here, the reader is directed to the Bibliography.
These sources will provide the information needed to gain a
qualitative understanding of seismology and the techniques of
seismometry. Some sources describe the construction of
seismometers and recording systems which can be constructed by
electronic hobbyists.
*1 IBM is a trademark of International Business Machines
Corporation.
1.1 Copyright Notices
Elements of the Amateur Seismology Package (also referred to as
'the package') are identified by the phrase 'part of the Amateur
Seismology Package.' Those elements which are copyrighted contain
a copyright notice. This notice appears near the beginning of
documents, on the opening screen of programs, and is encoded in
ASCII near the beginning of data files. The phrase 'all rights
reserved' means a person or organization other than the author
may copy and distribute elements of the package only under those
conditions defined in the 'Distribution' portion of this manual.
In particular, no element of the package may be distributed
unless accompanied by this user's manual.
The Amateur Seismology Package User's Manual 3
1.2 Disclaimer
The author hereby disclaims all warranties relating to the
Amateur Seismology Package. All elements of the package are
provided 'as is' and are not guaranteed to be suitable for any
particular purpose.
1.3 Distribution
The Amateur Seismology Package may be duplicated and distributed
by persons or organizations other than the author subject to the
following conditions:
Elements may be duplicated for backup purposes as desired.
Modified elements may not be distributed.
Elements may be distributed as long as no fee is charged
other than a nominal fee to cover the cost of the media
used.
If distributed via a bulletin board system (BBS), no
additional charge beyond normal connect time or access fees
may be made.
Any element distributed must be accompanied by The Amateur
Seismology Package User's Manual.
2.0 User Support
The first two versions of this package (versions 1.0.0 and 1.1.0)
requested a support fee from users in exchange for adding the
user's name to a mailing list. The solicitation of a support fee
implied that this package was 'commercial'.
Many information resources (networks, government funded BBS's,
etc.) do not permit such solicitation of funds. In order to
promote the free flow of information, I have decided to
discontinue the solicitation of a support fee and distribute the
package and data files free of charge. However, my copyright and
the restrictions set forth in the 'Distribution' portion remain.
Since a support fee is no longer being solicited, users are asked
to include return postage if requesting information via mail.
Users are also asked to remember that this is the author's
'hobby' and that the demands of home and career will have a
higher priority.
The Amateur Seismology Package support address is contained in
the copyright notice. Support can also be obtained by contacting
the author via electronic mail on CompuServe (ID 70531,3012) or
either of the BBS's on which this package is distributed (address
messages to user name Robert Samuelson).
The Amateur Seismology Package User's Manual 4
There is no telephone support for this package. Please use
electronic mail when possible.
3.0 Data File Distribution
The primary location for this package and the activities
associated with it will be the 'Mahoney MS-DOS file collection'
of the EXEC-PC BBS. EXEC-PC can re reached at (414) 789-4210
(use 8 data bits, no parity, 1 stop bit). EXEC-PC access costs
about $20 for three months or $60 for one year. You may
subscribe online. Even if primary distribution eventually moves
to another BBS, the files will continue to be distributed in
parallel on EXEC-PC at least through the end of 1992.
The author is not associated with EXEC-PC and cannot guarantee
that EXEC-PC will always be available. Any questions about EXEC-
PC should be directed to its sysop.
Beginning September 25, 1991, this package and data files will
also be distributed via the NEIC BBS on a trial basis (see
Bibliography).
Users are encouraged to form their own networks and post the data
files regularly on other BBS systems.
This package and the data files were originally distributed
through CompuServe (*1). The change to EXEC-PC was made largely
due to the fact that files uploaded to EXEC-PC are immediately
available while uploads to CompuServe can take a day or more to
become available. Also, CompuServe's service agreement appears
to frown upon the practice of systematically copying files from
CompuServe to other systems. This is not to say that users
cannot post these files on CompuServe, just that the author will
be using another service as the primary distribution point.
The author is currently using PKZIP (*2) and PKUNZIP for file
compression. These utilities are usually distributed as the
self-extracting file PKZ110.EXE. PKZ110.EXE (or a newer version)
is available on most BBS system. Remember that the PKWARE
packages also depend upon user support.
*1 CompuServe is a registered mark of CompuServe, Inc.
*2 PKZIP and PKUNZIP are trademarks of PKWARE, Inc.
The Amateur Seismology Package User's Manual 5
The data file for a given event will be a created from several
individual data files and an optional text file. The individual
data files will each contain ten minutes of data and will have
names of the form mmddhhmm.dat, where mmddhhmm represents the
month, day, hour, and minute of the file time stamp. The event
data file will have a name of the form yymmddhh.zip, where
yymmddhh represents the year, month, day, and hour of the first
.dat file of the event.
For example, 'unzipping' the event file 91070612.zip yields
07061226.dat, 07061236.dat, 07061246.dat, 07061256.dat, and
91070612.txt.
As detailed information about the events becomes available, a
bulletin file (probably named seisbull.zip) will be updated.
All files uploaded will have the word 'earthquake' or
'seismology' in the file description to aid online searches.
4.0 Bibliography
These sources will help the reader gain an understanding of some
aspects of the sciences of seismology and seismometry. The local
library or an encyclopedia is the best place to start.
Users finding a useful source of information are encouraged to
contact the author so this bibliography can be expanded.
Special thanks to those users who have already responded with new
sources.
Bolt, B. A. 1978. "Earthquakes, A Primer". W. H. Freeman and
Company, San Francisco.
Bolt, B. A. 1980. "Earthquakes and Volcanoes". W. H. Freeman
and Company, San Francisco. ISBN 0-7167-1164-8.
This book is a collection of articles which appeared in
Scientific American.
Bolt, B. A. 1976. "Nuclear Explosions and Earthquakes, The
Parted Veil". W. H. Freeman and Company, San Francisco.
Eiby, G. A. 1980. "Earthquakes". Van Nostrand Reinhold Company,
New York. ISBN 0-442-25191-2.
This book provides an excellent introduction to the study of
earthquakes and seismology.
Jeffreys, H. and Bullen, K.E. 1967. "Seismological Tables".
This book contains the 'JB' tables used to determine the
distance between a seismometer and an earthquake based upon
the difference in arrival times of the different types of
waves. It is probably out of print. If anyone does find a
source for this book or the JB tables, please notify the
author.
The Amateur Seismology Package User's Manual 6
Kalmbach Publishing Co. "Earth Magazine".
This magazine is a new spinoff from Astronomy Magazine. It
focuses on the Earth sciences. No articles on seismology as
yet, but it appears to be a good source of information for
the Earth science student. Kalmbach Publishing Co., 21027
Crossroads Circle, P.O. Box 1612, Waukesha, WI 53187.
Subscription inquiries (800) 446-5489.
Mims, Forrest M. III. 1990. "Engineer's Mini-Notebook Science
Projects". Radio Shack (catalog number 276-5018).
This book contains several electronic science projects,
including an 'earth movement sensor' and analog data logger.
Neumann, F. 1960. "Principles Underlying the Interpretation of
Seismograms". U.S Department of Commerce, Government Printing
Office.
Science Probe, Inc. "Science PROBE! Magazine".
This magazine has mentioned amateur seismology, and will
probably present items of interest in the future. The
October 1991 issue contains an article "Science Online",
which describes BBS systems of interest to Amateur
Scientists. Subscription address: Science PROBE!,
Subscription Department, P.O. Box 54097, Boulder, CO 80322-
4097.
Simon, R. 1981. "Earthquake Interpretations, A Manual for
Reading Seismograms". William Kaufmann, Inc.
Stong, C. L. 1960. "The Scientific American Book of Projects For
the Amateur Scientist". Simon and Schuster, New York. Library
of Congress Catalog Card Number 60-14286.
This book is a classic collection of articles which appeared
in the Amateur Scientist column in Scientific American
during the 1950's. Three of these articles describe amateur
seismology and the construction of seismometers and
seismographs. The electronic information is dated, but the
basic information is still useful. The hardcover version of
the book is long out of print. There was a subsequent
paperback version, but is also probably out of print. This
book is a good starting point. The torsional seismometer
kit mentioned in "The Attractions of Amateur Seismology" is
no longer available.
Stong, C. L. 1975. The Amateur Scientist Column of Scientific
American, September, 1975. "Electronic stratagems are the key to
making a sensitive seismometer." Scientific American Inc., New
York.
This article describes an electronic seismograph suitable
for construction by an electronic hobbyist.
Stong, C. L. 1979. The Amateur Scientist Column of Scientific
American, July, 1979. Scientific American Inc., New York.
This article describes an electronic seismograph suitable
for construction by an electronic hobbyist.
U.S. Geological Survey. Bimonthly. "Earthquakes & Volcanoes".
This publication contains articles of interest to students
The Amateur Seismology Package User's Manual 7
of Earth science and the general public. It is available
from the Superintendent of Documents, U.S. Government
Printing Office, Washington, DC 20402. Order from GPO at
(202) 783-3238 (VISA or MASTERCARD). Also try 'go gpo' on
CompuServe.
U.S. Geological Survey. Monthly. "Preliminary Determination of
Epicenters".
This publication (commonly known as PDE) contains a listing
of earthquakes for a given month along with the origin time,
location, depth, magnitude, etc. This publication is a few
months behind; for example the issue containing earthquakes
for July, 1990 was published in February, 1991.
Subscriptions are available from the Superintendent of
Documents or try 'go gpo' on CompuServe (see above). For a
more timely source of this information, see the online
sources, below.
Online sources:
NEIC BBS:
This BBS is operated by the National Earthquake
Information Center (NEIC). The sysop has agreed to
create an area on this board to contain the Amateur
Seismology package and associated files. This may also
be a good place for users to exchange ideas and
information. This BBS can be reached at (303) 236-0848
(setup no parity, eight data bits, 1 stop bit).
QED (Quick Epicenter Determinations):
This system is also operated by the NEIC. The QED
system may be used to access NEIC epicenter
determinations for events from about two days to one
month old. A description of this system and the
procedures to follow to connect it are contained in the
file QED.DOC in the SEIS file collection on the NEIC
BBS, above.
Try the online news wire services offered on CompuServe and
perform a keyword search on 'earthquake.' Beware: news
services do not always use UTC.
The Amateur Seismology Package User's Manual 8
5.0 SEISGRAPH - A Program for Viewing and Printing Seismograms
SEISGRAPH is a computer program which allows the user to load
seismic data files, select a portion of interest for viewing, and
print the image displayed on a dot matrix printer.
5.1 Overview
SEISGRAPH is designed to run on IBM PC compatibles with Hercules,
CGA, EGA, or VGA graphics. SEISGRAPH is written in Borland Turbo
C (*1) and makes use of the Quinn-Curtis Science/Engineering/
Graphics Tools (part #IPC-TC-006) (*2).
This program is not especially fast or sophisticated. It is
intended to be an inexpensive alternative to the many excellent
(but expensive) data plotting software packages available.
Since this program supports features for monitors and printers
that the author does not have access to, it was not possible to
fully test this program (for example, it has never been tried on
a system with CGA graphics). It is hoped that by carefully using
the Quinn-Curtis tools, which have been tested on many systems,
most problems have been avoided. It is certain that this program
contains undetected 'bugs'. This statement is based upon
experience as a programmer and a software tester.
The detection of bugs depends upon the users. Those who use the
program in a predictable way on a limited variety of data files
may never have a problem. Those who take fiendish delight in
stressing software (sometimes called 'malicious users') will
probably encounter problems. Malicious users are a quality
conscious programmer's best allies. Oddly enough, it seems to be
a curious fact that many malicious users are named Al or Allen.
The author encourages the reporting of bugs and freely admits
that the users are performing the quality control function.
*1 Turbo C is a trademark of Borland International, Inc.
*2 This product is a trademark of Quinn-Curtis. For
information on this and other tools, contact: Quinn-Curtis,
21 Highland Circle, Needham, MA 02194 USA
5.2 Installation
It is assumed that the user has some experience with installing
PC software. The installation procedure is very simple.
This package is usually distributed in the form of a ZIP files
which contain this manual, the SEISGRAPH program, and a sample
data file.
Copy the SEISGRAPH program (sg.exe) and the sample data file
(sample.dat) to a directory (for example c:\seis). In order to
run the program while in another directory without having to type
c:\seis\ before each command, it will be necessary to add c:\seis
The Amateur Seismology Package User's Manual 9
to the PATH.
If you are an inexperienced user and have problems, seek the help
of a more experienced user.
5.3 Guided Tour
The easiest way to explain this program is to walk the user
through a sample session. The first step is to install the
software as described above.
Change the default directory to the directory in which the above
files were installed or make sure the PATH has been properly set.
To invoke SEISGRAPH, type the following at the prompt followed by
return:
sg sample.dat
As SEISGRAPH executes, the following will appear on the screen:
The copyright notice and support address.
Reading data file: sample.dat
Reading setup string: S10
Samples per second: 10
Time stamp: 910308114539.5
The copyright notice encoded in the data file and any
additional text describing the contents of the data file.
Samples read: 6000
First sample: 2065
Last sample: 2179
Press ESC to quit or any other key to continue.
Press the ESC key. The prompt should reappear and the computer
should behave normally, allowing you to do a DIR or any other
command. This verifies that SEISGRAPH was able to allocate
memory, read the data file, and deallocate memory without
clashing with any other software that may be running on your
computer. If the computer is not operating normally at this
point or a message appeared that was not listed above, you have
found a bug (sorry Al). Proceed to the Problems and Solutions
section.
If things have gone well so far, invoke SEISGRAPH again and press
the space bar (or any key other than ESC).
The screen will go blank, the borders of several boxes will be
drawn on the screen, and all but two of the bordered boxes will
disappear as other information is placed on the screen.
Across the top of the screen is an area called the 'stamp
window.' At the left side of the window is the file time stamp.
This contains the time of the first sample in the file in the
format 'yr mo da ho:mi:se.t', where yr is the year, mo is the
month, ho is the hour, mi is the minute, se is the second and t
is tenths of a second. ALL DATES AND TIMES ASSOCIATED WITH
The Amateur Seismology Package User's Manual 10
SEISMIC DATA WILL BE IN UTC. At the right side of the window is
data describing the active range of y values in the format 'y_min
y_span y_max' where y_min is the smallest value to be plotted,
y_max is the largest value to be plotted, and y_span is the
difference of y_max and y_min.
Along the left side of the screen is a narrow vertical strip
called the 'guide y window.' At the top of this window is a
(partially obstructed) + sign and at the bottom is a (partially
obstructed) diamond. These marks are used to graphically show
the relative locations of y_min and y_max.
Along the top of the screen, below the stamp window and to the
right of the guide y window is the 'guide window.' This window
will be used to display the entire data file at a reduced scale,
making it possible to plot a small section of the file and still
'get the big picture.'
Directly below the guide window is the 'guide x window.' This
window is used like the guide y window to show the locations of
'x_min' (the first sample to be plotted) and 'x_max' (the last
sample to be plotted) relative to the entire file.
Directly below the guide x window is the 'x text window.' This
window is used to show the times associated with x_min and x_max
in the format min:sec and the sample number within the file
between the []. The time difference between x_min and x_max (the
span of time to be plotted) is centered in the x text window.
Directly below the guide x window is the largest of the windows,
the 'data window.' This is where the data bounded by y_min,
y_max, x_min, and x_max will be plotted.
To the left of the data window is the 'data y window' and
directly below the data window is the 'data x window.' The
functions of these windows parallel the functions of the guide y
and guide x windows, respectively.
Press the 'g' key. The entire data file will be plotted in the
guide window. Depending on the speed of your computer, this may
take from 3 to 30 seconds. After the data is plotted, an x axis
will be drawn in the guide window with tick marks at one minute
intervals (the tick marks may be too small to see).
Notice the diamond mark at the far left of the guide x window.
Press the right arrow key once. The diamond will move to the
right one tick along the x axis, and the x text window will be
updated to show that x_min has increased by one minute.
Press the space bar. The diamond on the left of the guide x
window will change to a + and the + on the far right of the guide
x window will change to a diamond. This signifies that x_max is
now the active limit.
Press the left arrow key twice. Notice that x_max decreases by
two minutes. Press the right arrow key once. Notice that x_max
increases by one minute.
The Amateur Seismology Package User's Manual 11
In general, a diamond indicates that the corresponding limit is
active and will be adjusted when an appropriate arrow key is
pressed. The left and right arrow keys affect only x_min and
x_max while the up and down arrow keys affect only y_min and
y_max. Pressing the space bar changes between adjusting the min
or max limits.
Using the space bar and arrow keys, adjust the y_min and y_max
values in the guide y window and the x_min and x_max values in
the guide x window until an area of interest in the guide window
is bounded by the four limits.
Press the 'g' key. The guide window will be redrawn, with the
y_min and y_max values selected, but the entire file will be
plotted, not just the area between x_min and x_max. This is
because the guide window is designed to show the entire file. In
fact, it is desirable to redraw the guide window with different y
limits only if the initial y limits do now allow enough detail to
be shown. The autorange feature (see Features, below) makes it
possible to draw the guide window once with limits set based upon
the actual minimum and maximum values of the data in the data
file.
Press the 'd' key. The area of interest selected will now be
plotted in the data window. An x axis will be drawn along the
bottom of the data window with tick marks at 10 second intervals.
The four limits can be adjusted again. The guide x and guide y
marks will show which area of the entire file will be plotted in
the data window the next time the 'd' key is pressed and the data
x and data y marks will show the same area but in greater
precision since the data marks relate to the data window which is
at a different scale than the guide window.
The steps by which the limits move in response to the arrow keys
is adjusted by the function keys. The effect of each key is
described in the Features section, below.
Press the ESC key to exit.
The sample data file used during this tour shows the p and s wave
arrivals (at 30 seconds and 8 minutes 23 seconds into the file,
respectively) recorded in Minnesota from an earthquake which
struck near the northern end of the Kamchatka peninsula at about
1136 UTC. This is an excellent file, not all events are recorded
this well.
This completes the guided tour. Read the Features section and
experiment to gain an intuitive understanding of the operations
of the various features.
The Amateur Seismology Package User's Manual 12
5.4 Features
The features of this program are presented in detail below
roughly in the order they were used in the guided tour.
5.4.1 Invoking SEISGRAPH
SEISGRAPH is started by typing the name of the program, an
optional 'setup string', and the name of the data file to be
examined. In the example above, no setup string was used. The
setup string can be used to change some of the ways SEISGRAPH
executes. See the Setup String section, below, for details.
5.4.2 Reading Data Files
After displaying the copyright message, SEISGRAPH reads the data
file specified on the command line.
The first portion of the data file contains a setup string which
contains information about the format of the data file. In most
cases, the only information contained in this setup string will
be the rate at which data was sampled. The setup string is read
and displayed. Any actions taken as a result of the information
contained in the string will be displayed. In the example above,
the setup string S10 was found and was interpreted as meaning
that the data in the file was sampled at 10 samples per second.
The second portion of the data file contains the file time stamp
which will be displayed in the stamp window. This is the time of
the first sample in the file.
The next portion of the data file contains text such as copyright
information or a description of the file contents.
Finally, the data portion of the file is read. SEISGRAPH can
read a maximum of 32767 samples and will stop reading the data
file when this many samples have been read. Also, only an
integral number of seconds worth of data will be read and any
extra data will be discarded.
When finished reading the data, SEISGRAPH will display the number
of samples read and the value of the first and last sample.
5.4.3 Adjusting X Limits
The x_min and x_max limits are adjusted using the left and right
arrow keys. The limit denoted by the diamond shape is the active
limit which will be changed in response to the arrow keys. The
active limit is chosen by pressing and releasing the space bar
until the desired limit changes from a + to a diamond.
The function keys F1 through F4 determine the step size for x
limit adjustments as follows:
F1 1 second steps
F2 10 second steps
The Amateur Seismology Package User's Manual 13
F3 1 minute steps (default at program start)
F4 10 minute steps
The TAB key moves the range of x values to the 'next' interval
and the SHIFT-TAB key moves the range of x values to the
'previous' interval.
The END key moves the active x limit to the end of the current
data window if the active x limit is currently within the current
data window. Otherwise it moves the active x limit to the
beginning or end of the file.
The x limits will not come closer together than the current x
step size and TAB/SHIFT-TAB will not move the x range if there is
not enough room left between the current range and the beginning
or end of the file.
5.4.4 Adjusting Y Limits
The y_min and y_max limits are adjusted using the up and down
arrow keys. The limit denoted by the diamond shape is the active
limit which will be changed in response to the arrow keys. The
active limit is chosen by pressing and releasing the space bar
until the desired limit changes from a + to a diamond.
The function keys F5 through F9 determine the step size for y
limit adjustments as follows:
F5 1 count steps
F6 10 count steps
F7 100 count steps
F8 1000 count steps (default at program
start)
F9 10000 count steps
The HOME key performs different functions depending upon whether
the 'autorange' feature is enabled. When autorange is not
enabled, the HOME key moves y_min to 0 and moves y_max to a
reasonable value (65535, 16383, 4095, 1023, or 255) depending
upon the largest data value in the file. When autorange is
enabled, the HOME key moves y_min to the smallest value and y_max
to the largest value present in the file. See the autorange
feature, below, for instructions on enabling autorange.
The y limits will not come closer together than the current y
step size.
5.4.5 Autorange
The autorange feature is enabled and disabled by the F10 function
key. When enabled, 'Autorange' will be displayed in the stamp
window. Autorange is not enabled when the program starts, but
this can be changed through the use of the setup string.
The Amateur Seismology Package User's Manual 14
5.4.6 Guide Window
The guide window is used to display a plot of the entire file.
The guide window is drawn when the 'g' key is pressed.
5.4.7 Data Window
The data window is used to display a plot of the portion of the
file bounded by x_min, x_max, y_min, and y_max. The data window
is drawn when the 'd' key is pressed. The data window can be
drawn with grids along the x axis by pressing the 'x' key or with
grids along both the x and y axes by pressing the 'b' key.
The timestamp can be displayed in the data window by pressing the
't' key and the x and y limits can be displayed in the data
window by pressing the 'i' key. These features are useful when
printing the data window.
5.4.8 Printing
The plot displayed in the data window can be printed by pressing
the 'p' key.
The portion of the plot on the right of the data window will be
the first portion printed.
When printing the contents of an entire file, select a range of x
values which divides evenly into the file length (so each print
operation will use the same scale), press TAB until the end of
the range coincides with the end of the file, and press 'p'.
When finished printing this segment, press SHIFT-TAB to move the
range toward the beginning of the file, press 'd' to draw the new
range of data, and press 'p'. Repeat this process until the
beginning of the range coincides with the beginning of the file.
Unfortunately, the printer driver inserts a blank space between
print operations. It is necessary to 'back up' the paper between
operations or cut and paste the resulting plots. Note that no
tick mark is drawn at the left or right end of the x axis.
An alternative to backing up the paper or cutting and pasting
plots is to press 'c' (for 'continuous printing') instead of
'p'. This causes a modified version of printer driver 5 to be
used, regardless of which printer driver has been selected. This
modified driver does not insert the blank space between print
operations. Unfortunately, this modified driver may leave a
small portion of data unprinted. It is not perfect, but it works
well and is a good alternative for users of Epson FX printers.
For more details on this printer driver, see the Setup String
section.
Although time and range data normally do not appear in the data
window, they may be displayed by pressing the 't' and 'i' keys,
permitting them to be printed along with the data plot.
The Quinn-Curtis tools support a number of printers and
The Amateur Seismology Package User's Manual 15
resolutions. For details on selecting the proper configuration
for your printer, see the Setup String section.
5.4.9 Setup String
The setup string is a series of letters and numbers which can be
placed in a data file and/or on the command line to affect the
way SEISGRAPH performs certain operations. When a setup string
is encountered, SEISGRAPH displays the string and also displays
the information extracted from the string.
For example, invoking SEISGRAPH with a setup string (s50ea):
sg s50ea sample.dat
will cause SEISGRAPH to assume the data was sampled at 50 samples
per second, that the data is eight bit data, and will enable the
autorange feature.
Any information contained in the command line setup string will
override any similar information in the data file setup string.
For instance, if the data file contains the setup string s10
(interpreted as 10 samples per second) and the command line
contains the setup string s5 (interpreted as 5 samples per
second), the 5 samples per second value will be used.
The following sections describe the options available through use
of the setup string. The default values described are the values
SEISGRAPH will use unless overridden by the setup string.
5.4.9.1 b (Binary File)
When a 'b' appears in a setup string, the data file will be
assumed to be a binary file (which contains only data) and not a
mixed file (which contains a setup string, timestamp, and
possibly text information). It makes no sense to place a 'b' in
a setup string in a data file since a binary file by definition
contains no setup string.
Placing a 'b' in the command line setup string enables the user
to read any file as a data file. This option is intended to at
least make it possible to read files other than those which are a
part of the Amateur Seismology Package.
If a binary file has been read, no file timestamp will be
available.
By default, SEISGRAPH expects data files to be of the mixed type.
The Amateur Seismology Package User's Manual 16
5.4.9.2 e (Eight Bit File)
When an 'e' appears in a setup string, the size of the samples in
the data file will be assumed to be one byte instead of the
default size of two bytes.
This option makes it possible to read data files which contain
eight bit information but do not fill the extra byte with zeros.
5.4.9.3 x (Skip Bytes)
An 'x' followed by a number in a setup string will cause
SEISGRAPH to skip that number of bytes before beginning to read
and store data. The number of bytes to skip must be <= 32767.
Note that this is the number of BYTES to skip, which will not be
the number of samples to skip if the sample size is TWO bytes.
This option makes it possible to read mixed files which have all
their text information grouped together by placing a 'b' and an
'x' followed by the appropriate number of bytes in the setup
string.
The default value of Skip Bytes is 0.
5.4.9.4 c (Color)
Placing a 'c' followed by a number in the setup string permits
the user to choose which color SEISGRAPH will use.
The following list is based upon the table for the Turbo C
setallpalette function. The CGA values have not been tested.
The default value of Color is 63.
CGA EGA/VGA
0 black black
1 blue blue
2 green green
3 cyan cyan
4 red red
5 magenta magenta
6 brown
7 light gray light gray
8 dark gray
9 light blue
10 light green
11 light cyan
12 light red
13 light magenta
14 yellow
15 white
20 brown
56 dark gray
57 light blue
58 light green
59 light cyan
60 light red
The Amateur Seismology Package User's Manual 17
61 light magenta
62 yellow
63 white
5.4.9.5 a (Autorange)
Placing an 'a' in the setup string enables the autorange feature.
This makes it possible to have autorange enabled when the program
starts instead of having to press F10 HOME SPACE HOME before
drawing the guide window.
By default, autorange is not enabled.
5.4.9.6 s (Samples Per Second)
An 's' followed by a number in the setup string determines the
sample rate SEISGRAPH will use. Samples per second must be <=
32767.
Samples per second is normally set in the data file, but may be
changed on the command line. This feature is useful when reading
binary data files.
The default value of Samples Per Second is 10.
5.4.9.7 b (Bin Size)
A 'b' followed by a number in the setup string determines the bin
size used when drawing in the guide window. The number must be
>= 2 and <= 32767.
Instead of plotting every point in the guide window (which can be
very time consuming), data is grouped into bins and the maximum
value and the minimum value for each bin is plotted.
Making the bin size small increases the fidelity of the plot in
the guide window but slows down the plotting process due to the
increased number of bins which must be plotted. Making the bin
size large decreases the fidelity of the plot but speeds up the
plotting process.
The default value of Bin Size is 10.
5.4.9.8 p (Printer Port)
A 'p' followed by an number in the setup string determines which
printer port SEISGRAPH will use. The number must be 0 (for
LPT1:) or 1 (for LPT2:).
The default printer port is LPT1:.
The Amateur Seismology Package User's Manual 18
5.4.9.9 d (Printer Driver) and r (Resolution)
Placing a 'd' or 'r' followed by a number in the setup string
selects which printer driver and resolution will be used when
printing the image contained in the data window. The user needs
to determine which driver and resolution are appropriate for the
printer being used.
The following table is taken from the documentation for the
Quinn-Curtis ScreenDump function. The author has only tested
this package using drivers 5 and 99.
The default value for Printer Driver is 5 and the default value
for Resolution is 0.
Important note: The author made some modifications to the Quinn-
Curtis source code (function GetVertByte in screen.c) to speed up
screen dumps at the expense being unable to scale the screen
dumps in the x and y directions. GetVertByte is used by drivers
0, 2, 5, and 99. These modifications were tested with drivers 5
and 99 and should work with drivers 0 and 2. If troubles are
encountered while using drivers 0, 2, 5, or 99, please notify the
author and do not blame the Quinn-Curtis tools.
Another important note: The author made some modifications to
the Quinn-Curtis source code (function EpsonFXScreenDump, driver
5) to eliminate the space between print operations. This
modified driver (99) may leave a small amount of data unprinted,
but it is a good alternative to backing up the paper or cutting
and pasting plots. In order to use this driver, press 'c'
instead of 'p' to print the screen, or use the setup string to
select driver 99 and press 'p' to print the screen.
Driver:
0 Epson MX driver
1 Epson LQ driver
2 Toshiba P driver
3 HP Laser Jet driver
4 HP Ink Jet driver
5 Epson FX driver
99 Modified (no gap) Epson FX driver
Resolution:
Epson MX, FX drivers
0 single density normal speed
1 double density half speed
2 double density normal speed
3 quadruple density
Epson LQ driver
0 single density normal speed 8 pin mode
1 double density half speed 8 pin mode
2 double density normal speed 8 pin mode
3 quadruple density 8 pin mode
4 standard density 24 pin mode
5 double density 24 pin mode
6 CRT III 24 pin mode
7 triple density 24 pin mode
The Amateur Seismology Package User's Manual 19
8 hex density 24 pin mode
Toshiba P driver
0 180x180 dot image transfer
1 180x360 dot image transfer
HP Laser Jet driver
0 75 dots/inch
1 100 dots/inch
2 150 dots/inch
3 300 dots/inch
5.5 Data File Format
SEISGRAPH can be used to read almost any kind of data file
(except ASCII formats, commonly used by spreadsheet programs).
This flexibility is provided by the 'b', 'e', 'x', and 's'
options in the setup string.
The data files distributed with SEISGRAPH and the data files
periodically distributed following earthquakes will be in a
'mixed' format. The mixed format is described below. Users with
data acquisition capability are encouraged to use this format to
facilitate the exchange of files.
The first portion of a mixed file is a setup string. This string
may contain all of the types of information that a setup string
on the command line may contain, but it should be limited to
contain just the samples per second information.
The second portion is the file time stamp. This string should be
in the format described in the guided tour section. The time
stamp in the sample files includes tenths of a second but uses
spaces for place holders for hundredths and thousandths of a
second. This is to provide the ability to use more precise file
time stamps in the future.
The third portion is plain text.
All strings must be 80 characters or fewer in length and must be
terminated with a newline character ($0A).
When SEISGRAPH encounters two newline characters in a row, the
rest of the data file will be assumed to be binary data.
Data files can be examined using a 'dump' utility or an editor
which has the capability to edit binary files. Trying to use a
text editor on a data file may cause undesired results, possibly
corrupting the data file.
5.6 Problems and Solutions
The following is a list of possible error messages, the probable
cause, and the appropriate actions.
Bad command or file name
PC users are used to this one. The user either mistyped sg,
The Amateur Seismology Package User's Manual 20
the file sg.exe is not in the current directory, or sg.exe
is not in the current directory and the path has not been
properly set. Get help from a more experienced PC user.
No <optional setup string> or data file name on command line.
Usage: SG <optional setup string> data file name.
The user typed sg but did not specify a setup string or data
file name.
OUT OF MEMORY.
Unable to create guide data array.
Program terminated.
SEISGRAPH was unable to find enough memory to hold a maximum
and minimum value for each bin. This is due to a small bin
size which results in the need for a large number of bins.
Increase Bin Size using the 'b' option in the setup string.
OUT OF MEMORY.
Unable to create data array.
Program terminated.
SEISGRAPH was unable to find enough memory to hold 32767 two
byte samples. Either the system does not have enough memory
or other programs are using the rest or the memory. Try
running SEISGRAPH without any other programs (TSR utilities,
etc.) present.
Error opening file:
SEISGRAPH was unable to find the specified data file. If
the filename displayed looks like the setup string, it is
because the command line contained a setup string and no
data file or the data file was entered on the command line
before the setup string.
No data read.
Program terminated.
SEISGRAPH read the data file but did not find any data. This
may be because there were not two newline characters in a
row after the end of plain text in a mixed file or because
Skip Bytes was set to a number larger than the total number
of samples in the file.
Less than one second of data or > 32767 samples per second.
Program terminated.
SEISGRAPH read the data file but did not find at least one
second's worth of data or Samples Per Second was set >
32767. Reduce Samples Per Second using the 's' option in
the setup string.
Problem with registerbgidriver call.
Program terminated.
One of the registerbgidriver calls returned an error
response. This should never happen unless sg.exe has
somehow become corrupted.
CANNOT FIND DRIVER FILE.
Program terminated.
SEISGRAPH was unable to correctly identify the graphics
adapter installed in the computer. SEISGRAPH will not work
The Amateur Seismology Package User's Manual 21
with this graphics adapter.
6.0 How Data Files Are Created
The seismometer used to produce the data files is a horizontal
pendulum with a period of about 20 seconds. The transducer is a
moving coil - fixed magnet type producing a velocity response.
The seismometer output is filtered, amplified, and sampled at a
50 Hz rate by an analog to digital converter (A to D) card
installed in a PC.
The file time stamp is read from a Heath GC-1000 at the beginning
of each data file. This clock is synchronized to WWV and is
usually accurate to 0.01 second, but the computer interface only
reports time to the nearest 0.1 second (the delay introduced by
the data transfer between the clock and computer is not presently
known exactly, but it is less than 0.1 second). The Heath clock
is very accurate but the clock on the A to D card which actually
controls the sample rate tends to drift. This is confirmed by
the fact that the file time stamps do not differ by exactly ten
minutes. A rough rule of thumb to follow until the system timing
is examined and a better clock is used to control the sample rate
is that times are accurate to within about one second.
The seismometer is located at approximately 45 degrees north
latitude and 93 degrees 20 minutes west longitude. The pendulum
is aligned along a roughly north-south axis and is therefore most
sensitive to motion in the east-west direction.
The calibration of the system is rather rough at the present
time. Pendulum movement toward the east with respect to the base
of the seismometer (the equivalent of ground movement to the
west) results in samples with higher values.
The filter and amplifier are simple and uncalibrated. If enough
user support materializes, a better amplifier and filter will be
built and calibrated.
Although the sample rate is 50 Hz, the files are reduced to a
sample rate of 10 Hz and compressed with PKZIP before
distribution. If this were not done, the files would be large
and would require a much longer time (and more money) to
download.
The effective sample rate of 10 Hz is sufficient for amateur
uses. However, some of the noise picked up by the seismometer
(traffic, trains, etc.) may contain frequencies higher than 5 Hz.
Those familiar with the Nyquist theorem know that this causes
'aliasing'. If enough supporting users want data without this
aliasing, an anti-aliasing filter will be installed or the
digital data will be filtered before being converted to a 10 Hz
sample rate.
The Amateur Seismology Package User's Manual 22
7.0 The Future
Plans for additions and enhancements to this package include:
A program for converting data files to/from the ASCII
formats used by other plotting/spreadsheet programs.
Moving the seismometer to a quieter location.
Adjusting the amplifier gain or sampling at two or more
different gains so large amplitude waves do not saturate the
A to D card.
Calibrating the amplifier gain and filter response so the
data is more useful.
The Amateur Seismology Package is intended to promote interest in
the Earth sciences. If amateur seismology becomes a popular and
useful tool in this respect, it is hoped that organizations with
access to better seismic data will make this data available on a
regular basis.
The Amateur Seismology Package User's Manual 23
----------------end-of-author's-documentation---------------
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